Fire alarm



Jan. 22, 1957 D. M. JACOBY 2,778,330

FIRE ALARM Filed May 5, 1953 2 Sheets-Sheet 1 INVENTOR. DAVID M. JACOBY ATTORNEY.

Jan. 22, 1957 JACQBY 2,778,330

FIRE ALARM Filed May 5, 1953 2 Sheets-Sheet 2 l/l/lA INVENTOR.

DAVID M. JACOBY United States Patfifl Q Fire Alarm Co. Incorporated, Philadelphia, Pa., a corporation of Pennsylvania Application May 5, 1953, Serial No. 353,136

2 Claims. (Cl. 116-106) The present invention relates to audible alarms and particularly to heat-sensitive alarms.

The present invention is a continuation-in-part of my application Serial No. 274,389, filed March 1, 1952.

An object of the present invention is to provide an etficient and highly sensitive fire alarm.

Another object of the present invention is to provide a relatively small-size portable self-contained fire alarm capable of giving a signal for a relatively long period of time.

Another object of the present invention is to provide a gas-operated fire alarm wherein all of the gas is efiiciently used to create an audible signal.

Another object of the present invention is to provide a dependable and inexpensive fire alarm.

Further objects will be apparent by reference to the appended specification, claims and drawings.

For the purpose of illustrating the invention, there are.

shown in the accompanying drawings forms thereof which are at present preferred, although it is to be-understood that the various instrumentalities of which the invention consists can be variously arranged and organized and that the invention is not limited to the precise arrangements and organizations of the instrumentalities as herein shown and described.

In the drawings wherein like reference characters indicate like parts,

Figure 1 represents a perspective view of one embodiment of the alarm of the present invention, with the cover removed therefrom.

Figure 2 represents a top plan view of the alarm shown in Figure l with the cover shown in horizontal crosssection.

Figure 3 represents a fragmentary vertical crosssectional View taken generally along line 3-3 of Figure 2.

Figure 4 represents a perspective view, partly in section, of another embodiment of the alarm of the present invention.

Figure 5 represents a fragmentary elevational view, partly in section, of the valve-closure at the top of the vessel shown in Figure 4.

Figure 6 represents a vertical cross-sectional view of the connector-member intervening the tubular conduit and the horn of the alarm shown in Figure 4.

Figure 7 represents a fragmentary elevational'view, partly in section, of that portion of the conduit of the alarm shown in Figure 4 wherein the fusible element is disposed.

Figure 8 represents a top plan view of the bracket for securing the trumpet to the vessel of the alarm shown in Figure 4.

In the embodiment of the alarm of the present invention which is illustrated in Figures 1 to 3, inclusive, there is shown a vessel 10 which is preferably a thick-walled container capable of withstanding high internal pressure. At the top of the vessel 10 a cap-and-valve 11 is operatively secured, as by interengagement between the 2,778,330 Patented Jan. 22, 1957 ICE 2 I threads 12 on the cap 11 and the threaded aperture 13 at the top of the vessel 10. i

A ball-check valve 14 is disposed within the bore 15 in the cap 11; a spring 16 urging the ball 17 against the valve-seat 18. The spring 16 is held in place within the bore 15 by a cylindrical. spring-seat 19 which may be press-fitted or otherwise secured in the bore 15.

A closure is detachably secured in the outer end of the bore 15, as by being screw-threaded therein.

The cap 11 may be externally threaded at its outer end, as at 21, so as to permit the filling of the vessel 10 through the cap 11. This is done by removing the closure 20 and operatively securing a hose or other conduit (not shown) to the threaded portion 21 of the cap 11, whereupon the operating material is introduced past the ball-check valve 14 through the bore 15 into the vessel 10. The ball 17 is forced against the seat 18 by the spring 16 so as to prevent escape of the operating material from the vessel 19 upon removal of the filler hose from the threaded portion 21 of the cap 11. Thereafter the closure 20 is replaced to provide an additional gas-tight seal for the end of the bore 15.

A transverse passageway 22, approximately .028 inch in diameter, extends radially from the bore 15 between the ball 17 and the inner end of the bore 15. The passageway 22 terminates in a threaded counterbore 23. In the passageway 22 intermediate the bore 15 and counterbore 23 a fusible plug 24 is operatively secured in a pressure tight manner so as effectively to seal the passageway 22 against the passage of fluid or gas from the interior of the vessel 10.

The fusible plug 24 may be any low-melting-point alloy:

particular fusible material but I have found that an alarm wherein the signal is given when the room temperature reaches F. to have widest application.

Secured within the threaded counterbore 23 is one end of a rigid conduit 25. The bore 26 inthe conduit 25 terminates in a pocket 27 and provides a passageway and repository for the fusible plug'24. When the melting point of the fusible plug is reached, the pressure of the gases within the vessel 10 and bore 15 and passageway 22' forcibly blow the plug 24 out of the passageway 22 andv through the bore 26 of the conduit 25 into the pocket 27.

A bypass 28 is formed in the conduit 25 with the inner end spaced axially from the pocket 27 in communication with the bore 26 and with its other end 29 terminating within the cavity 30 of the air-horn 31.

After the fusible plug 24 has-been forced by gaspressure into the pocket 27, the gases pass from the bore 26 through the bypass 28, while the plug 24 remains lodged in the pocket 27. v

The horn 31 may be any gas-operated signal-sounder but is, preferably, of the gas-operated diaphragm-type. The horn illustratedin Figure 3 has a generally cupshaped housing 32 having an aperture 33 therein, in which aperture one end of the conduit 25 is operatively secured.

A diaphragm 34 is disposed across the upper end of the cavity 30 and is held in place at the top of the cup-shaped housing 32 by the cap 35 which is detachably secured to the cup 32 as by the screws 36.

An adjustable tube 37 is secured in the bore 38 at the lower end of the cup 32 and has its upper edge 39 in contact with the under surface of the diaphragm 34.

A portion of the outer surface of the tube 37 may be screw-threaded, as at 40, and secured in matingscrewthreads 41 in the aperture 38 so that relative rotary motion between the tube 37 and the cup 32 will adjust the pressure which the end 3? of the tube 37 exerts against the under surface of the diaphragm 34. i

A locking-nut 42 may be secured to the threaded outer surface of the tube 37 exteriorly of the cup .32 whereby to secure the tube against rotation with respect to the cup 32.

Adjustment of .the end 3? of the tube 37, so as to vary the pressure exerted against the diaphragm 34, causes variation in the pitch of the sound emanating from the tube 37 and trumpet 43.

p A trumpet 43 is secured to the outer end or the tube 37 and is constructed and arranged to amplify the sound generated by the horn 31 and emanating from the tube 37. 1

When the atmosphere surrounding the alarm shown in Figures 1 to 3, inclusive, is heated above the melting point of the plug 24, with simultaneous heating of the filler-cap 11, the plug 24 melts and is dislodged from the passageway 22 by the pressure within the vessel 10, whereupon the plug is blown into the pocket 27 andthe gas under pressure escapes through the bypass 28 into the cavity 30, where it forces the diaphragm 3.4 upwardly away from the end 39 of the tube 37. A small amount of the gas passes through the gap between the tube 37 and the diaphragm 34- and escapes from the tube and trumpet 43. Thereupon the diaphragm returns to its initial position, setting up a sound-wave in the tube 37 and trumpet 43 which creates anaudible signal which is amplified by the trumpet 43. Thereafter the diaphragm 34 is again forced outwardly by the gas under pressure within the cavity 30 and thereupon still more gas escapes through the tube 37. As long as the gas under pressure passes into the cavity 30 the diaphragm 34 will be vibrated and the soundwaves will be generated within the tube 37 and amplified by the trumpet 43.

I prefer to use, as. an operating gas, dichlorodifluoroe methane (Freon) which, under normal room temperatures, is a liquid. However, at operating temperatures, it changes to a gas. The same increase in temperature which causes melting of the fusible plug 24 also changes the operating substance from a liquid to a gas. The period of time during which the alarm of the present invention will operate is relativelylong because a given volume of dichlorodifluoromethane at room temperature will expand to such a greater volume at operating temperature as to provide sufiicient volume of gas to operate the horn for a long time-interval. Moreover, the diameter of the passageway 22 and bypass 28 is such as to prevent instantaneous discharge of the gas from the vessel 10.

Moreover, all of the operating material is utilized inasmuch as all of it is conducted through the conduit 25 directly to the cavity 30 whereupon it operates the highly efficient diaphragm-type horn shown in the drawings and described above. Very little gas-pressure is required to vibrate the diaphragm 34 and the horn continues to create an audible signal until the pressure in the vessel is reduced to atmospheric pressure, i

The vessel 10, cap 11, conduitZS, horn 31 and trumpet 43 are preferably encased within a cover 44 which is decorative and which is easily secured to a supporting surface (such as the wall 45) by the brackets 46 on the screws 47.. r 3

It has been found desirable, under some circumstances, to connect the cover 44 directly to the cap 11 by a heatconducting strip (not shown) so that as soon as the cover 44 is heated to operating temperature the cap 11 will be 4 I not be impeded when the operating material, under pressure, is introduced into the cavity 30.

In Figures 4 to 8, inclusive, there is shown another embodiment of the present invention. This embodiment is similar to the embodiment illustrated in Figures 1 to 3, inclusive, and described hereinabove.

However, the conduit 48 in this embodiment is preferably a relatively thin-walled tube of copper or the like. The conduit 48 may be threaded, at one end, as at 49, and secured in a correspondingly threaded passageway 222-5: which extends radially outwardly through the cap ll-a from the bore 15-a.

In addition to the screw-threaded connection between the conduit 48 and the passageway 22a, I prefer to weld the tube 48 to the cap 11-a, as at 50, so as to provide a fluid-tight and gas-tight connection between the conduit 43 and the passageway 22-a.

The other end 51 of the conduit 48 is securely coupled to a connector 25-a which is similar to the conduit 2-5 heretofore described. The connection between the end 51 of the conduit 48 and the connector 25a may be by the threaded nut 52 andthe bead 53 formed adjacent the end 51 of the conduit 48.

Intermediate the end 49 and the nut 52, the conduit 48 is crimped or otherwise reduced in diameter, as at 54, and a fusible plug is'operatively disposed in the conduit 48 at the reduced portion 54.

The reduced portion 54 is preferably tapered and the plug 55 is correspondingly tapered, with the larger end being exposed to the gas under pressure within the vessel 10 and the conduit 48. Thus, the gas pressure may assist in forcing the plug 55 tightly within the constriction 54 to provide a gas-tight and fluid-tight seal between the plug 55 and the constricted portion 54 of the conduit 48.

I prefer to form the conduit 48 in such a manner that the constricted portion 54 is in contact with the cover 44a, as isshown particularly in Figure 4. The conduit 48 may be held in close contact with the cover id a by the-bracket 56. This construction insures that the conduit 48 and plug 55 are heated instantly to the same temperature as the cover 44-11 and surrounding atmosphere.

As soon as the plug 55 is heated to operating temperature, it melts and is forced past the constriction 54 by the gas-under-pressure, passing through the conduit 48 into the pocket 27-a of the bore 26-(1 in the connector 25-11. Thereafter the gases may escape through the bypass 28-a into the cavity 30 of the horn 31.

Because the conduit 48 is relatively flexible, I prefer ,to secure the horn 31 and trumpet 43 securely in relation heated to the same temperature and thus the plug 24 will to the vessel 10 by a bracket or other support 57. The bracket 57 may be in the form of a multiple hose-clamp, as illustrated in Figure 8. However, I do not mean to limit myself to any specific form of bracket or clamp.

The vessel 10, horn 31 and trumpet 43, as well as the intervening conduit 48 (or 25) may be secured with-in the cover 44 (or 44-11) by any brackets or other clamps (not shown). I prefer to use detachable brackets which permit the removal of the vessel 10 from the cover 44 so as to permit recharging of the vessel 10 through the cap 11 and re-inserting of a fusible plug 24 (or 54) after the alarm has been rendered operative, whereupon the alarm may be used again in the same manner as described above.

The present invention may be embodied in other specific forms withoutdeparting from the spirit or essential attributes thereof, and it is therefore desired that the present embodiments be considered in all respects as illustrative and not restrictive reference being had to the appended claims rather than to the foregoing description to indicate the scope of the invention.

Having described my invention, 1 claim:

1. 1A fire alarm including a generally cylindrical vessel containing gas under pressure, an outlet on the longitudinal axis .of said vessel for permitting the escape of gas from said vessel, a gas-operated sound-creating instrument having an inlet through which gas is passed to actuate the instrument, a conduit interconnecting the outlet of said vessel and said instrument for permitting gas released from said vessel outlet to he passed through said instrument and to sound said gas-operated soundcreating instrument, a portion of said conduit disposed perpendicular to the longitudinal axis of said vessel, a fusible plug in said conduit for preventing passage of gas from said vessel to said instrument, a plug-receiving cavity in communication with said conduit, said plug receiving cavity constructed and arranged to receive the. plug, said cavity being disposed out of the plane of the center axis of the inlet of said gas-operated sound-creating instrument.

2. A fire-alarm including a vessel containing gas under pressure, a gas-operated sound-creating instrument, a conduit connecting said vessel and said instrument, said conduit having a small-diametered portion nearer said vessel than to said sound-creating instrument, a fusable plug in said small-diam'etered conduit and nonmally sealing the same, said conduit having a larger-diametered portion intermediate the so-sealed smaller-diametered portion thereof and said sound-creating instrument, said larger-diametered portion terminating in a pocket for receiving the material of said fusable plug when it is melted, said pocket and said larger-diametered portion being in alignment with each other and with said smalldiametered portion so that when the fusable plug is melted the force of the gas under pressure Will project the material of said fusable plug through the larger-diametered portion of said conduit into said pocket, and a passageway disposed transversely of said larger-diametered portion of said conduit and communicating therewith and extending therefrom to said sound-creating device and so arranged in relation to said larger-diametered portion of said conduit and said smaller-diametered portion and said pocket that when the fusable plug is melted insaid smaller-diametered portion of said conduit and is projected through the larger-diametered portion thereof, towards said pocket, it will not enter said transverse passageway.

References Cited in the tile of this patent UNITED STATES PATENTS 1,105,888 Davis Aug. 14, 1914 2,034,179 Franklin Mar. 17, 1936 2,211,142 Loudon Aug. 13, 1940 2,483,657 Messick Oct. 4, 1949 2,506,983 Williams May 9, 1950 2,649,752 Showstack Aug. 25, 1953 2,696,798 Jacoby Dec. 14, 1954 FOREIGN PATENTS 418,342 Great Britain Oct. 23, 1934 

